1. Field of the Invention
The present invention is related to a pivot bearing provided on support structures formed of shaped bars, which, in particular, is secured to and moved by robot arms, and which is used for attaching tools, such as clamping, suction, gripping equipment and/or the like tools.
2. Description of the Prior Art
Shaped bars of the afore-described type are used for assembling support structures which, in turn, are especially intended for attachment to robot arms and for securing tools such as clamping, suction and gripping equipment and/or other working equipment.
The shaped bars intended for the afore-described purposes that are interconnected by corresponding clamping elements correspondingly conforming in profile, as a rule, are profiles of octagonal configuration which, in turn, are normally provided with not less than two radially opposite notches. Bars of octagonal profiles are preferably used for the afore-mentioned purposes to enable the clamping elements of conforming profiles to be mounted in eight different orientations to the shaped bars, depending on the orientation in which the tools referred to in the afore-going by way of example, are to be seated on the support structure, and, furthermore, depending on the orientation intended for crossing shaped bars held by the same clamping element. No direct and stepless adjustment of orientation of tools of the afore-described type relative to shaped bars of polygonal configuration of the afore-mentioned type, through a clamping element, hitherto, has been possible so that a special configuration of the clamping elements has been required to the effect that they had to be combined with a pair of turntables in the event that a stepless displacement was desired, with such a procedure involving substantial efforts.
For further details regarding special clamping elements adapted to be mounted to shaped bars, reference is made to U.S. Pat. No. 4,032,245.
However, UK Patent Application GB 2 275 737 A also teaches support structures of this type wherein the support bars are made of cylindrical sectional tubes. As the shaped bars irrespective of whether they are of a cylindrical or polygonal configuration, are of drawn material, inevitable inaccuracies will occur which are likely to result in inaccuracies of adjustment of attached tools of the afore-mentioned type. Moreover, it is not possible to safeguard a torque-resistant seat in all radial orientations by clamping alone.